A multi-disciplinary group has been assembled to make a concerted effort to increase our knowledge of reproductive physiology and biochemistry. The unit has been constituted by bringing together several smaller, heretofore, more or less independent groups. The disciplines now represented comprise: clinical investigation, neuroanatomy and physiology, animal biology and surgery, biochemistry, immunochemistry, mathematics and bioengineering. Specific objectives for the immediate future are the understanding of: mechanisms of regulation of the menstrual cycles in humans and primates, the application of control theory to problems of reproduction, the biosynthesis of the gonadal and adrenal hormones, their rates of secretion, metabolism, and entry into the cell, and finally, the interaction between the gonadal hormones and their tissue receptors. It is hoped that besides increasing our fundamental knowledge about the reproductive processes, the efforts of the new unit will lead to new approaches for the treatment of abnormal reproductive function and open the way to novel techniques of contraception.